Composite materials are essential for many modern applications, includingairplanes and cars, energy conversion and storage devices, medical prosthetics, and civilstructures. The strength and life of such materials are determined by a complexsequence of progressive nucleation, accumulation, and coalescence of micro-damagethat is always related to the micro-morphology of the constituents and their properties.Although detecting and modeling all of the discrete events in that sequence is quitedifficult, and in some cases not feasible, it would be very useful to identify observableparameters that indicate the onset of different stages of damage development so thatremaining strength and life could be estimated. Recently, the authors have developed amethod of following the effect of multi-defect nucleation, growth, coalescence, andfracture plane development based on the measurement of dielectric response ofcomposite materials. The method also enables the prediction of as-manufacturedindividual sample strength, suggesting that the birth-to-death effect of defects can befollowed and interpreted. The present paper postulates the construction of a fundamentalfracture mechanics methodology based on this general set of observables that couldenable the consistent relationship of all defect and material states during the processingand application life of composite materials as a foundation for a birth-to-deathassessment of the effect of defects. The “heterogeneous fracture mechanics” concept isdefined and discussed with example data and observations that indicate the success andlimitation of the method for as manufactured materials, static and fatigue loadings.
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